1. Field of the Invention
The present invention relates to titanium lubricating material suitable for use in vacuum as light material for constructing a space station, for example, and more specifically to a technology of improvement in surface quality of lubricating material usable for analysis instruments used in space or vacuum.
2. Description of the Prior Art
Conventionally there exist martensite-based stainless steels (e.g. AISI440C), high-chromium bearing steels (e.g. SUJ2), etc., as lubricating material suitable for use in vacuum.
To improve the surface quality of these substrates, the following technologies have been so far proposed:
(1) Nitriding onto the surface thereof (as disclosed in Japanese Published Unexamined (Kokai) Pat. Appli. No. 1-261561), and
(2) Ion implantation onto the surface thereof (as disclosed in Japanese Published Unexamined (Kokai) Pat. Appli. No. 1-205072).
In the prior-art lubricating material suitable for use in vacuum, since the substrate is made of iron, there exists a problem in that the weight thereof inevitably increases.
Further, when light alloy such as aluminium alloy or titanium alloy is used in such an environment, since the substrate is soft and therefore there exists a big difference in elastic deformation rate between a solid lubricating film and the substrate when used as lubricating material, there exists a problem in that bonding force is reduced at the boundary between the two and thereby the life time of the solid lubricating film is shortened.
Therefore, there exists a need of development in lubricating material suitable for use in vacuum, which is light in weight and long in life time of the solid lubricating film.